A perimeter foundation that has tipped, bowed, or severely cracked requires substantial reinforcement or replacement to prevent further deterioration.
Washed-out areas
If a broken water pipe, a plugged gutter, or a drainage problem in your yard sent enough water cascading alongside a perimeter foundation to undermine an area, a contractor might be able to shore up the area with more concrete or shim the sill plate to make the area level again. Or you might need to tear out a section of the foundation, re-pour, and tie the new section into the old with rebar and epoxy.
Foundations and expansive soils
If your house is out of kilter and there is no obvious reason, it may sit on soil that expands when damp and shrinks when dry. This so-called expansive soil is found in all states and has damaged about a quarter of all houses in the U.S., according to the American Society of Civil Engineers. If you suspect you have the problem, check with your local building authority to see if expansive soils exist in your area.
Dealing with this kind of soil is most difficult if you have a slab foundation because access is to underneath the slab is limited. First, try to reduce moisture fluctuations under your house. Make sure soil slopes away from the house, and pipe away all gutter water. Replace water-thirsty landscaping within 5 feet of the walls with plants that need little water or, even better, install a concrete path around the house so rainwater can’t soak in there.
Working with a structural engineer
Trustworthy advice comes from a structural engineer. If you need a full engineering report, expect to pay several thousand dollars. You might also need a soils engineer and core samples, doubling the cost.
Professional estimates from foundation-repair contractors make sense if you live in a neighborhood where one solution has succeeded in similar homes.